Driving method of lcd device and driving system

ABSTRACT

A driving method of a liquid crystal display (LCD) device includes a step A and a step B. In the step A, using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency, generating a target image signal based on the target frequency. In the step B, performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal.

TECHNICAL FIELD

The present disclosure relates to the field of liquid crystal displays (LCDs), and more particularly to a driving method of an LCD device and a driving system.

BACKGROUND

Because liquid crystal display (LCD) devices have low energy consumption and a small volume, they are widely welcomed by consumers.

Because deflection reaction speed of liquid crystals (LCs) of the LCD devices is not high enough, display effect of the LCD devices may not be optimum, so an overvoltage drive is used to accelerate reaction speed of the LCs. In the overvoltage drive, an additional voltage load is decided by a previous image state and a current image state of the LCD device. A voltage of overvoltage drive is decided by a last pixel in a previous-frame image and a first pixel in a current-frame image of the LCD device.

As gray scales of different pictures are different and the voltages in the overvoltage drive are also different, an overvoltage driving table is arranged in the LCD device to conform to a corresponding overvoltage output and obtain an expected picture gray scale. However, along with an input of source image signals of different frequencies, using a three-dimension (3D) shutter type LCD device as an example, output frequencies of image signals are also changed. In this way, due to different output frequencies, the overvoltage drive is inaccurate and a displayed brightness curve (gamma curve) of the gray scales is poor, thus increasing image crosstalk. If the overvoltage driving tables of different frequencies are combined, more memory is used, which increases costs, thus disadvantageous to controlling costs.

Certainly, when a two-dimensional (2D) image is displayed and the input frequencies are different, as the overvoltage drive is inaccurate, the displayed brightness curve of the gray scales is also poor and the expected display effect may not be achieved.

SUMMARY

In view of the above-described problems, the aim of the present disclosure is to provide a driving method of a liquid crystal display (LCD) device and a driving system for reducing crosstalk and saving costs.

The purpose of the present disclosure is achieved by the following technical scheme: a driving method of an LCD device comprises steps:

A: using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency of 65 Hz, generating a target image signal based on the target frequency of 65 Hz; and

B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal;

in the step A,

if a frequency of the received source image signal is lower than the target frequency, generating a new frame picture, inserting evenly the new frame pictures among frame pictures of the source image signal in a frequency cycle to generate a new image signal, where a frequency of the new image signal being same as the target frequency;

if the frequency of the source image signal is greater than the target frequency, selecting partial pictures from the source image signal, and discarding the selected partial pictures, wherein the selected discarded partial pictures are evenly extracted from the frame pictures of the source image signal in one frequency cycle of the source image signal.

The purpose of the present disclosure can also be achieved by the following technical scheme:

a driving method of an LCD device comprises steps:

A: using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency, generating a target image signal based on the target frequency; and

B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal.

In one example, the target frequency is greater than 45 Hz.

In one example, the target frequency is greater than 60 Hz. As two commonly used frequency types in the prior art are 50 Hz and 60 Hz, the preferred target frequency is greater than 60 Hz. The source image signal is not discarded to obtain a better effect when viewing by human eyes.

In one example, the target frequency is 65 Hz. The preferred target frequency is 65 Hz. As two commonly used frequency types in the prior art are 50 Hz and 60 Hz, for 50 Hz, only 1 frame picture is compensated for each three frames. For 60 Hz, only one frame picture is added behind each 11 frames. For 65 Hz, a smaller integer interval is used. To match the two main types, fewer pictures are inserted. Only one picture compensation mode is adopted, with simple design. Moreover, experimental data displays that when the target frequency is selected as 65 Hz, better visual effect can be achieved and human flash perception can be reduced.

In one example, in the step A, if the frequency of the received source image signal is lower than the target frequency, generating a new frame picture, and inserting the new picture into the source image signal to generate a new image signal, where a frequency of the new image signal being same as the target frequency. The frequency of the source image signal achieve the target frequency adding new frame pictures, thus adapting to one overvoltage driving table.

In one example, in the step A, the new frame pictures are evenly inserted among frame pictures of the source image signal in one frequency cycle of the source image signal. The evenly inserted mode enables picture display to be smoother. Simple or complicated compensation pictures are selected according to the number of the frame pictures to be inserted, thus obtaining better display effect.

In one example, the new frame pictures inserted into the source image signal are a totally black picture, a totally white picture, an action detection compensation picture generated by computation, a previous-frame picture, or a next-frame picture. Simple or complicated compensation pictures are selected according to the number of the frame pictures to be inserted, thus obtaining better display effect.

In one example, in the step A, if the frequency of the source image signal is greater than the target frequency, selecting partial pictures from the source image signal, and discarding the selected partial pictures.

In one example, in the step A, the selected discarded partial pictures are evenly extracted from the frame pictures of the source image signal in one frequency cycle of the source image signal.

A driving system of an LCD device is configured with a conversion module converting a source image signal having a different frequency from the target frequency into a preset target frequency. The display device uses one overvoltage driving table matching with the target frequency.

In the present disclosure, the source image signal having the different frequency from the target frequency is converted into the new image signal having the target frequency. In this way, the LCD device only uses one overvoltage driving table to display the image signals of different frequencies without causing a poor brightness curve of gray scales, saving a lot of memory, which saves the cost. For a three-dimensional (3D) display device, different frequencies of a left-eye image signal and a right-eye image signal are converted into the target frequency so as to share one overvoltage driving table, which reduces flash and crosstalk. For a two-dimensional (2D) display device, it is suitable to image input of other frequencies, and the display achieves a better display effect.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a principle diagram of a driving method of a liquid crystal display (LCD) device of the present disclosure;

FIG. 2 is a composition diagram of a driving system of a liquid crystal display (LCD) device of the present disclosure;

FIG. 3 is a schematic diagram of conversion of a source image signal and a system structure in a first example of the present disclosure;

FIG. 4 is a schematic diagram of conversion of a left-eye source image signal in a first example of the present disclosure;

FIG. 5 is a schematic diagram of conversion of a right-eye source image signal in a first example of the present disclosure;

FIG. 6 is a signal fluctuation chart after converting an image signal in a first example of the present disclosure;

FIG. 7 is a contrast diagram of visual perceptions of signals of different frequencies; and

FIG. 8 is a composition diagram of a driving system of a liquid crystal display (LCD) device in a third example of the present disclosure.

DETAILED DESCRIPTION

The present disclosure is further described in detail in accordance with the figures and the preferable examples.

As shown in FIG. 1, the present disclosure discloses a driving method of a liquid crystal display (LCD) device, comprising steps:

A: using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency, generating a target image signal based on the target frequency; and

B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal.

As shown in FIG. 2, the present disclosure also discloses a driving system of an LCD device, comprising:

a conversion module 20 converting a source image signal, where a frequency of the source image signal is different from a target frequency, into a new image signal with a preset target frequency; and

an overvoltage driving module 30 only using one overvoltage driving table matching with the target frequency.

In the present disclosure, the source image signal having the different frequency from the target frequency is converted into the new image signal having the target frequency. In this way, the LCD device only uses one overvoltage driving table to display the image signals of different frequencies without causing a poor brightness curve of gray scales, saving a lot of memory, which saves costs. For a three-dimensional (3D) display device, different frequencies of a left-eye image signal and a right-eye image signal are converted into the target frequency so as to share one overvoltage driving table, which reduces flash and crosstalk. For a two-dimensional (2D) display device, it is suitable to image input of other frequencies, and the display achieves a better display effect.

For the step A, if the frequency of the received source image signal is lower than the target frequency, generating a new frame picture, and inserting the new frame picture into the source image signal to generate a new image signal, where a frequency of the new image signal being same as the target frequency.

For the step A, if the frequency of the source image signal is greater than the target frequency, selecting partial pictures from the source image signal, and discarding the selected partial pictures.

According to the above driving method, the present disclosure is further described by a specified example of the driving system of the LCD device.

Example 1

As shown in FIG. 2, the driving system of the LCD device comprises a conversion module 20 and an overvoltage driving module 30. As shown in FIG. 3, the conversion module comprises a buffering module 21 and a compensation module 22. The buffering module 21 is internally configured with a buffering controller of two pictures, a buffer memory connected with the buffering controller, and a fixed frequency clock. The compensation module 22 comprises a compensator, a static buffering memory, a buffer, an X-frame picture counter, and a data output port.

As shown in FIG. 3, the example is described by converting a left-eye source image signal of a 3D shutter type display device of 60 Hz into a target image signal with the target frequency of 65 Hz. When the left-eye source image signal enters a buffering controller of two pictures of the buffering module 21, the fixed frequency clock is used to perform an action detection to a Nth picture and a (N+1)th picture and store the two pictures into the buffering memory. Then, the Nth picture and the (N+1)th picture are simultaneously inputted into the compensator and the buffer of the compensation module 22. A compensation picture X is generated in the compensation module 22 and stored into the static buffering memory. The pictures in the buffer are normally outputted. At this moment, the X-frame picture counter is used to control the data output port to control output of the compensation picture as needed (inserting into the source image signal). At a moment (the moment of inserting the compensation picture X, obtained by computation), the compensation picture X is inserted between the Nth picture and the (N+1)th picture and is outputted together with the Nth picture and the (N+1)th picture. Each frame picture outputted is stored in the picture memory by the overvoltage driving module 10 and is contrasted with the overvoltage driving table for image output control.

This is an example that the processed left-eye source image signal of 60 Hz enters the overvoltage drive output. For a right-eye source image signal of 50 Hz, the compensation mode is the same. Certainly, the frequencies of the left-eye signal and the right-eye signal are not limited to the numerical values cited in the example.

In the example, the new frame picture inserted into the source image signal, i.e. the compensation picture X, is a totally black picture, a totally white picture, an action detection compensation picture generated by computation, a previous-frame picture, or a next-frame picture. If the number of the pictures to be inserted is small, simple pictures, such as the totally black picture, the totally white picture, the previous-frame picture, or the next-frame picture can be selected. If the number of the pictures to be inserted is large, the action detection compensation picture generated by computation can be selected so as to obtain a better display effect.

In the example, the number of compensation pictures X to be inserted is selected according to a difference between the frequency of the source image signal and the target frequency. The insertion chance can be even, random, or in a given point. As shown in FIG. 4, if the left-eye source image signal of 60 Hz is converted into a new image signal of the target frequency of 65 Hz, five-frame compensation pictures X are inserted. In the example, a mode that new frame pictures are evenly inserted among the frame pictures of the source image signal is used in one frequency cycle of the source image signal, namely one compensation picture X is inserted behind each eleven-frame picture of the source image signal. As shown in FIG. 5, if the right-eye source image signal of 50 Hz is converted into the new image signal of the target frequency of 65 Hz, fifteen-frame pictures are inserted. Thus, one compensation picture X is inserted behind each 3-frame picture. The evenly inserted mode enables picture display to be smoother. As shown in FIG. 6, a movement curve after compensation slightly shakes, but is not obvious under 3D view. As two commonly used frequency type signals, 50 Hz and 60 Hz, are selected in the example, and figures of 50 and 60 are a common divisor of 5, to better evenly insert the matching compensation pictures, the target frequency is a common divisor of 5 preferably. In the example, the selected 65 Hz is just the common divisor of 5. Alternatively, the target frequency can also be 55 Hz. However, two modes need to be used to change the frequency of the source image signal into the target frequency. One mode is to compensate the pictures, and the other mode is to discard the pictures. Thus, design difficulty and the cost are increased. For 65 Hz, a smaller integer interval is selected, and only the mode to compensate the pictures is used. Thus, there are fewer pictures to be inserted to match the two main types. In addition, FIG. 7 shows a schematic diagram comparing human flash perception to a brightness signal of a liquid crystal display screen that is subject to fourier transform at different frequencies. When the target frequency is selected at 65 Hz, the data in the table shows that a better visual effect can be achieved and human flash perception is reduced. Thus, in the example, the selected target frequency is 65 Hz.

In the example, frame pictures are compensated to the source image signal so as to achieve the target frequency corresponding to the overvoltage driving module 30, so that the overvoltage driving module 30 can correctly perform overvoltage drive. The target frequency is larger than 45 Hz so that human eyes may not feel the flash. Certainly, the target frequency is preferably larger than 60 Hz so that better effect is achieved when viewing by human eyes.

Example 2

The difference between a first example and a second example is that the left-eye source image signal is a sixty-frame signal and the target frequency is 55 Hz. Thus, the processing mode of the source image signal is to discard five-frame pictures so as to be consistent with the target frequency. At this moment, the five-frame pictures in the source image signal are removed by a compensation module. Certainly, the removal mode is even extraction from one frequency cycle of the source image signal, i.e. sixty-frame pictures. Or, one frame picture is evenly extracted every several pictures to be discarded. The right-eye signal has the same processing mode, namely corresponding frame pictures are added or reduced.

Example 3

The type of the source image signal and the frequency of target image signal in the first example and the second example are defined. Thus, signal determination is not needed.

For the example, a determination module of the image signals is added, so that one overvoltage driving table needed to perform drive output to different source image signals. As shown in FIG. 8, the driving system of the LCD device comprises a determination module 10, a conversion module 20, and an overvoltage driving module 30. The driving process is shown as follows:

A: determining whether a type of a received source image signal needs a frequency conversion, if yes, converting a display frequency the received source image signal into the target frequency, generating a target image signal based on the target frequency. Otherwise, the source image signal is the target image signal; and

B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal.

The present disclosure is described in detail in accordance with the above contents with the specific exemplary examples. However, this present disclosure is not limited to the specific examples. For example, if the frequency of the source image picture is consistent with the target frequency, no processing is required in the compensation module. For the ordinary technical personnel of the technical field of the present disclosure, on the premise of keeping the conception of the present disclosure, the technical personnel can also make simple deductions or replacements, and all of which should be considered to belong to the protection scope of the present disclosure. 

We claim:
 1. A driving method of a liquid crystal display (LCD) device, comprising: A: using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency of 65 Hz, generating a target image signal based on the target frequency of 65 Hz; and B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal; in the step A, if frequency of the received source image signal is lower than the target frequency, generating a new frame picture, evenly inserting the new frame pictures among frame pictures of the source image signal in a frequency cycle to generate a new image signal, wherein a frequency of the new image signal being same as the target frequency; if the frequency of the source image signal is greater than the target frequency, selecting partial pictures from the source image signal, and discarding the selected partial pictures, wherein the selected discarded partial pictures are evenly extracted from the frame pictures of the source image signal in one frequency cycle of the source image signal.
 2. A driving method of a liquid crystal display (LCD) device, comprising: A: using frequency conversion on a received source image signal when a type of the received source image signal is different from a preset target frequency, and converting a display frequency of the received source image signal into a target frequency, generating a target image signal based on the target frequency; and B: performing an overvoltage drive output using an overvoltage driving table matching with the target frequency of the target image signal.
 3. The driving method of the liquid crystal display (LCD) device of claim 2, wherein the target frequency is greater than 45 Hz.
 4. The driving method of the liquid crystal display (LCD) device of claim 3, wherein the target frequency is greater than 60 Hz.
 5. The driving method of the liquid crystal display (LCD) device of claim 4, wherein the target frequency is 65 Hz.
 6. The driving method of the liquid crystal display (LCD) device of claim 2, wherein in the step A, if frequency of the received source image signal is lower than the target frequency, generating a new frame picture, and inserting the new picture into the source image signal to generate a new image signal, wherein a frequency of the new image signal being same as the target frequency.
 7. The driving method of the liquid crystal display (LCD) device of claim 6, wherein in the step A, the new frame pictures are evenly inserted among frame pictures of the source image signal in one frequency cycle of the source image signal.
 8. The driving method of the liquid crystal display (LCD) device of claim 6, wherein the new frame pictures inserted into the source image signal are a totally black picture, a totally white picture, an action detection compensation picture generated by computation, a previous-frame picture, or a next-frame picture.
 9. The driving method of the liquid crystal display (LCD) device of claim 2, wherein in the step A, if frequency of the source image signal is greater than the target frequency, selecting partial pictures from the source image signal, and discarding the selected partial pictures.
 10. The driving method of the liquid crystal display (LCD) device of claim 9, wherein in the step A, the selected discarded partial pictures are evenly extracted from the frame pictures of the source image signal in one frequency cycle.
 11. A driving system of a liquid crystal display (LCD) device, comprising: a conversion module converting a source image signal having a different frequency from a target frequency into a preset target frequency, wherein the driving system of the LCD device uses one overvoltage driving table matching with the target frequency.
 12. The driving system of the liquid crystal display (LCD) device of claim 11, wherein the conversion module comprises a buffering module and a picture compensation module connected with the buffering module.
 13. The driving system of the liquid crystal display (LCD) device of claim 12, wherein the buffering module is configured with a buffer controller of two pictures, a buffering memory connected with the buffer controller, and a fixed frequency clock.
 14. The driving system of the liquid crystal display (LCD) device of claim 12, wherein the compensation module comprises a compensator, a static buffering memory connected with the compensator, a buffer, a compensation picture counter, and a data output port respectively connected with the buffer, the compensator, and the compensation picture counter.
 15. The driving system of the liquid crystal display (LCD) device of claim 11, wherein the driving system further comprises an image signal determination module determining a type of the source image signal. 